Greg Smith wrote:
> Merlin Moncure wrote:
> > I am right now talking to someone on postgresql irc who is measuring
> > 15k iops from x25-e and no data loss following power plug test.
> The funny thing about Murphy is that he doesn't visit when things are
> quiet. It's quite possible the window for data loss on the drive is
> very small. Maybe you only see it one out of 10 pulls with a very
> aggressive database-oriented write test. Whatever the odd conditions
> are, you can be sure you'll see them when there's a bad outage in actual
> production though.
>
> A good test program that is a bit better at introducing and detecting
> the write cache issue is described at
> http://brad.livejournal.com/2116715.html
Wow, I had not seen that tool before. I have added a link to it from
our documentation, and also added a mention of our src/tools/fsync test
tool to our docs.
--
Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: doc/src/sgml/config.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/config.sgml,v
retrieving revision 1.233
diff -c -c -r1.233 config.sgml
*** doc/src/sgml/config.sgml 13 Nov 2009 22:43:39 -0000 1.233
--- doc/src/sgml/config.sgml 28 Nov 2009 16:12:46 -0000
***************
*** 1432,1437 ****
--- 1432,1439 ----
The default is the first method in the above list that is supported
by the platform.
The <literal>open_</>* options also use <literal>O_DIRECT</> if available.
+ The utility <filename>src/tools/fsync</> in the PostgreSQL source tree
+ can do performance testing of various fsync methods.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
</para>
Index: doc/src/sgml/wal.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v
retrieving revision 1.59
diff -c -c -r1.59 wal.sgml
*** doc/src/sgml/wal.sgml 9 Apr 2009 16:20:50 -0000 1.59
--- doc/src/sgml/wal.sgml 28 Nov 2009 16:12:57 -0000
***************
*** 86,91 ****
--- 86,93 ----
ensure data integrity. Avoid disk controllers that have non-battery-backed
write caches. At the drive level, disable write-back caching if the
drive cannot guarantee the data will be written before shutdown.
+ You can test for reliable I/O subsystem behavior using <ulink
+ url="http://brad.livejournal.com/2116715.html";>diskchecker.pl</ulink>.
</para>
<para>
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